This article gives an overview about the various liver markers that are used in the clinical lab.

Steps

1

Know about the functions of the liver. The liver has an important function of proteins synthesis especially the group of proteins that are called immunoglobulins. These are also synthesized by the cells of the immune system. Proteins are usually synthesized in the liver from amino acids that are partially synthesized in the liver and partly are obtained in the diet in the form of food rich in proteins. Learn where are synthesized. The synthesis of proteins in the liver can be evaluated by two important liver tests. These are: the level of the protein albumin in the blood and the prothrombin time.

2

Learn about the protein albumin. Albumin is an important protein that usually has an important physiological function in maintaining the osmotic colloid pressure in the arteries. Its deficiency can cause edema and ascites in the body due to the decreased osmotic colloid pressure caused by the decreased amount of albumin in the blood. Albumin is the protein of choice in the clinical lab in order to test whether proteins synthesis in the liver is normal or not. Decreased amount of albumin in the blood or hypoalbuminemia signifies an impaired ability of the liver to synthesize proteins.

3

Learn about clotting factors of the blood. Also proteins of the coagulation factors are measured in liver tests for proteins synthetic capability of the liver through the prothrombin time. Elevated prothrombin time can signify a dysfunctional or impaired protein synthesis. This can result in bleeding tendency due to the lack of coagulation factors which are proteins that are synthesized in the liver. The liver cells function can be tested by measuring the amount of the amino transferases enzymes in the blood. These enzymes concentration in the blood are elevated in diseases of the liver that affect the hepatocytes.

4

Learn what causes liver injury. Examples of causes to liver cells damage are drugs that can be toxic to the liver cells. In addition, blood hypoperfusion of the liver cells such as occurs in condition of shock can lead to liver cell damage with subsequent development of elevated level of the amino transferase enzymes in the blood. Also blood hypoperfusion to the liver cells can be caused due to congestive heart failure. This causes in turn damage to liver cells which can be manifested by elevation in the level of these enzymes in the blood. Bilirubin is another marker for liver function. Its excess in the blood usually signifies an impaired transport of this pigment from the liver to the biliary canals due to either a defect in the liver cells or due to an obstruction in the biliary canal by a cholesterol stone.

5

Know about the pigment bilirubin. Bilirubin is a pigment that is usually obtained in the blood from the metabolism of the heme portion of the hemoglobin molecule. It usually accumulates in the blood due to a liver pathology or due to hemolytic anemia such as occurs in thalassemia and sickle cell disease of red blood cells. It can also accumulate in the blood as a result to an obstruction in the biliary canals in which the flow of bile into the intestine is blocked by a cholesterol stone that is lodged in the biliary canal.

6

Learn about alkaline phosphatase as a marker of liver disease. Biliary canal obstruction has a special marker which is an enzyme that is called alkaline phosphatase. This enzyme is usually secreted by bone cells and the liver. Also there are other sources to this enzyme in which it is secreted in small quantities in the intestine and the placenta in the pregnant woman. Alkaline phosphatase is secreted in excessive amount in the case of cholestasis or blocking of the biliary canal which can obstruct the flow of bile from the liver to the small intestine. This causes in turn jaundice.

7

Know about the liver marker alpha feto protein. The last liver marker that is discussed here is called alpha-feto protein. This marker is secreted to the blood circulation in increased amount in cancer of the liver. It can also be oversecreted by a malignancy such as a teratoma. For this reason this marker is a sensitive measure of liver cancer but is not specific for the liver function only.